Recently, due to developments in information technology, bidirectional communications may be performed actively via a packet communication network. IP (Internet Protocol) telephones use the VoIP (Voice over Internet Protocol) that enables audio communication via the Internet, by making transmission and reception via the packet communication network. It may be regarded that the amount of communications performed by the IP telephones via the packet communication network will increase in the future. Hence, for IP telephone service providers, the importance of monitoring and managing the speech quality is likely to increase.
On the other hand, in the field of portable telephones, an operation may be performed in accordance with the communication quality or, a service may be provided in accordance with the communication quality, by measuring the loss rate, delay, and the like of the packets flowing through the packet communication network.
However, in the related art, it may be difficult to specify the location where a failure is generated.